The flow cytometry laboratory consists of two FACScans and a FACStar Plus, all of which are on a thin wire ethernet using TCP/IP. There are three other FACScan and two FACSTAR flow cytometers within CBER; they all have some level of network capability. Together these laboratories make up the CBER/FDA flow cytometry consortium. The Section of Flow & Image Cytometry is concerned with desk-top publishing of flow cytometric data, development of necessary software programs to carry this out in the Macintosh graphics user interface environment, and quantitative flow cytometry as it relates to our regulatory needs. The next area of data analysis in flow cytometry will consist of a comparison of cluster analysis programs. The major program concerns the etiology and pathogenesis of common and familial B cell lymphocytic leukemia (BCLL). This has consisted of an evaluation of two and three color surface immunofluorescence, cell cycle analysis and sorting of B cells for PCR analysis of monoclonality. This latter activity is being undertaken as part of a linkage analysis study in familial B-CLL. It is designed to detect early preclinical CLL in third and fourth generation family members to facilitate the formal genetic linkage analysis. Presently, we use E-rosette depletion, monocyte depletion and magnetic beads to prepare enriched B lymphocyte preparations. Oligomeric primers for V-region families (VH1 through VH6) are used for clonal evaluation. An NZB mouse colony has been established to evaluate a murine model of B-CLL. Image analysis is being carried out to examine the morphological heterogeneity of lymphocytes seen on conventionally prepared blood films as a function of time. A linkage analysis in an F1 backcross is underway. A protocol of loss of heterozygosity is being prepared.